Charging and closing apparatus for concrete mixers



P 7, 1954 J. w. LENDVED ETAL CHARGING AND CLOSING APPARATUS FOR CONCRETE MIXERS 3 Sheets-Sheet 1 Filed Oct. 2, 1951 JOHN W LENDVED WILLIAM H.BUELOW INVENTOR ATTORNEY p 7 1954 J. w. LENDVED ETAL 2,688,472

CHARGING AND CLOSING APPARATUS FOR CONCRETE MIXERS Filed Oct. 2, 1951 3 Sheets-Sheet 2 p 7, 1954 J. w. LENDVED ETAL CHARGING AND CLOSING APPARATUS FOR CONCRETE MIXERS Filed Oct. 2. 1951 3 Shets-Sheet 3 FIG. 7.

JOHN W [LENDVED WILLIAM H. BUELOW INVENTOR$ ATTORNEY Patented Sept. 7, 1954 CHARGING AND CLOSING APPARATUS FOR CONCRETE MIXERS John W. Lendved and William H. Buelow, Milwaukee, Wis., assignors to Chain Belt Company, Milwaukee, Wis., a corporation of Wisconsin Application October 2, 1951, Serial No. 249,294

19 Claims. 1

This invention relates, generally, to rotary drum concrete mixers or the like and more particularly to improved hopper and closure apparatus for cooperating with the charging opening of a rotary mixing drum.

A general object of the present invention is to provide an improved combined charging hopper V and door for the charging opening of a rotary A further object is to provide improved actuating mechanism for a combined charging hopper and door arranged to lock the hopper and door in selected position.

According to the present invention, a rotary mixing drum, such as used in a concrete mixer of the inclined axis high discharge type presenting a coaxial charging opening at its upper end, is provided with an improved combined charging hopper and door structure. This combined structure is mounted for bodily movement toward or from the drum charging opening through pivoting movement of a supporting yoke, the structure being rotatably mounted in the yoke for tilting therein to either of two positions for presenting the hopper element or the door element to the drum opening selectively. The combined hopper and door is actuated by interlocked control apparatus arranged for operation from a readily accessible position and functioning selectively to perform the movements that select the hopper or the door and move the selected element into cooperating engagement with the drum charging opening. The coordinated control mechanism is so interlocked that the door and hopper structure can be tilted only while the structure is in a position remote from the charging opening. Locking apparatus is provided for locking the combined hopper and door in selected position to prevent accidental displacement.

The foregoing and other objects of this inven tion will become more fully apparent as the following. detailed description of an exemplary embodiment thereof is read in conjunction with the accompanying illustrative drawings, wherein:

Figure l. is a view in left side elevation of an improved combined hopper and door structure and associated control apparatus embodying the present invention, together with the rear portion of a truck-mounted concrete mixer to which it is applied;

Fig. 2 is a view similar to Fig. 1 but showing the combined hopper and door structure inverted and including a broken line position illustrating further movements;

Fig. 3 is an enlarged fragmentary view of parts of the structure shown in Fig. 2, some parts having been broken away to disclose internal structure;

Fig. 4 is an enlarged fragmentary detail view in section through the dust shield shown in elevation in Fig. 3;

Fig. 5 is a view of the mixer structure in rear elevation with the combined hopper and door disposed in the position shown in solid lines in Fig. 2;

Fig. 6 is an enlarged detailed view in vertical transverse section through the control gear box, taken on the plane represented by the line 6-6 in Fig. 5; and

Fig. 7 is a view in longitudinal section through the gear box, taken on the plane represented by the line 1-1 in Fig. 6.

The embodiment of the invention set forth herein by way of an illustration of a practical structural manifestation of the inventive concept constitutes an improved combined charging hopper and closure door for cooperating with the charging opening of a rotary mixing drum such as the drum of a concrete mixer of the truckmounted high discharge type represented in the drawings.

The particular truck-mounted high discharge mixer illustrated in part in the drawings by way of example may be of the type fully shown and described in the copending application of John W. Lendved filed August 3, 1951, Serial No. 240,141, although it is to be understood that the improved combined charging hopper and door apparatus may be applied with equal advantage to various other mixing drums of different construction.

Referring more specifically to the drawings and particularly to Figs. 1 and 2 thereof, the illustrative concrete mixer with which the improved hopper and door mechanism is arranged to cooperate is represented by a mixer drum NJ and its supporting frame I I, only the rear portions of which are shown. As explained in the copending application, the mixer drum H] is rotatably supported in the cooperating truck-mounted frame H with its rear or discharge end in elevated position, a rear upright or frame member 2! constituting the principal portion of the frame I l illustrated in the drawings. The mixing drum ii] is rotatable about its longitudinal axis I2 which is inclined upwardly and rearwardly in such a manner that the drum presents a coaxial charging and discharging opening It in an elevated position at the rear of the motor truck on which the mixer is mounted. As more fully explained in the previously mentioned copending application, the drum I0 is rotatably supported or cradled as shown in Fig. 5 in the rear upright member 2i 3 of the frame ll upon a pair of rollers 22 journalled in spaced relationship in the frame and cooperating with a cylindrical bearing ring or trackway 23 on the periphery of the drum I0. As best shown in Fig. 3, the drum in is provided on its internal surface with spirally arranged mixing blades 2! which operate to tumble and mix the concrete and to either feed it inwardly or eject it outwardly for discharging through the elevated discharge opening l5, depending upon the direction of rotation of the drum. As shown. the mixing blades 21 are provided along their inner edges with transverse or circumferential lips 23.

According to the present invention, the elevated charging and discharging opening 96 is adapted for functioning in the charging and mixing phases of a concrete mixing cycle through cooperating with a combined hopper and door structure or assembly 3|. The structure 3! includes a closure or door element 32 shown engaged to cover the opening it in Fig. 1 and a charging hopper 33 shown in Fig. 2 disposed in cooperating relationship with the charging opening it in the drum iii, an extending chute element 34 at the lower edge of the hopper serving to guide material fed through the hopper into the drum opening. As appears in the drawings, the door 32 and the hopper 33 are joined together in back-to-back relationship to constitute a unitary structure, either element of which may be engaged with the drum opening I6 selectively thereby to facilitate charging the drum or, alternatively, to retain the charged material in the drum during mixing and transporting thereof. To provide for the interchange of these elements, the assembly 3| is mounted for tilting movement in such a manner that it may be inverted to present either the door 32 or the hopper 33 to the opening it alternatively as may be desired. Furthermore, the assembly Ell is arranged for bodily swinging movement in order that it may be lifted or retracted from the opening it and lowered or advanced toward the opening, the arrangement being such that either the door or the hopper may thereby be moved into engagement with the opening, depending upon which is presented toward it at the time.

To provide for the desired bodily movement toward or from the opening it, the combined hopper and door structure 3! is movably supported on the mixer frame il by means of a rotatable transverse shaft 35 journalled in bear ings 38 mounted on the outer top rear corners of the mixer frame I! above the upper edge of the charging opening iii in the drum It. As best shown in Fig. 5, the cross shaft 35 has fixed to it a pair of spaced, radially extending, depending, parallel arms 31 that support the combined structure 3! between their outer ends for bodily pivotal movement thereof toward or from the opening it when the shaft 3E5 is turned. The cross shaft 35 and the arms 3i constitute in effect a supporting yoke with the outer ends of its arms rotatably engaging trunnions 38 on the opposite sides of the combined structure 3! to provide for tilting movement of the structure about the trunnion axis to present either the door 32 or the hopper 33 to the drum opening 16.

As shown in the drawings, the hopper element 33 has secured to its lower side or back a pair of spaced brackets 39 that are adjustably connected to a transverse supporting bar 40 that carries at its respective ends offset arms ll from which the trunnions 38 project into bearings at the outer ends of the pivoting arms 31. By this arrangement, the hopper 33 may be tilted upon the trunnions 38 to such position that its lower end or chute 34 may be introduced into the drum opening it between the lips 23 on the inner edges of the spiral mixing blades 27 as shown in Fig. 3, the proper position of the discharge chute 34 of the hopper, relative to the blade lips 23 being established by adjusting the mounting of the brackets 39 upon the supporting bar it.

To prevent the escape of dust from that portion of the opening 16 beneath the chute while the drum is being charged, the hopper S3 is provided with a semicircular depending dust shield or plate 42. As shown in detail in Fig. 4, the outer edge of the dust shield 42 is provided with a peripheral dust skirt 43 of rubber or like flexile material that yieldably engages the edge of the drum opening it and maintains close engagement therewith while permitting relative movement when the drum is rotated While material is being charged into it.

From the foregoing it will be understood that by pivotally revolving the combined hopper and door structure bodily about the axis of the cross shaft 35 and by tilting it about the trunnions 38, either the hopper element or the door element may be presented to and advanced into cooperating relationship with or retracted from the drum opening it selectively.

The closure element or door 32 is constituted by a dished circular cover plate that engages the edge of the drum opening is for closing it completely in the manner shown in Fig. 1 during mixing or transporting of the concrete. In order that the door element 32 may rotate with the drum It during the mixing operation, the door is rotatably mounted on a stub shaft or stud 4 secured to and projecting radially from the supporting bar 45 at the back of the hopper 33. As best shown in Fig. 3, the stub shaft -14 passes through an enlarged opening 45 in the center of the door 32 into a cylindrical cup-like housing 46 secured over the opening and projecting inwardly of the door 32. The stub shaft M- is preferably provided on its end within the door with an antifriction bearing ll that is supported within the housing 4% by a disk or diaphragm 16, the bearing being yieldably retained within a cavity in the disk 68 by means of a pressure plate til that is urgedagainst the bearing by springs til seated in the bottom of the housing it}. By this arrangement the cover 32 may be forced into firm engagement with the end of the mixing drum i D to close the charging opening it, the spring pressed plate 49 yielding as may be necessary to adapt the door to irregularities that may be present on the edge of the drum, in a manner to maintain a tight fit between the door and the drum.

The bearing 4? thereby adapts itself to permit free rotation of the door with the drum while maintaining the door in close engagement with the drum through the resilient action of the springs 5c. By arranging the bearing housing 46 inwardly of the door 32 as shown in the drawing, it is possible to mount the door close to the back of the hopper 33, thereby maintaining the overall dimensions of the combined unit 31 at a minimum to facilitate tilting movement thereof in presenting the door or the hopper alternatively to the drum opening 86.

As shown in the drawings, the cover plate constituting the door 32 is provided with three axially projecting centering lugs 5i equally spaced about its periphery. The three lugs 5| engage the inner edge of the drum opening i6 and guide the door into concentric relationship therewith as it is urged into closed position by the resilient rotary supporting structure.

Tilting movement of the hopper and door assembly 3| is effected by means of a sprocket 52 secured to the outer end of the trunnion 38 on the left side of the assembly as shown in Fig. 5. Aligned with the sprocket 52 on the trunnion is a complementary sprocket or drum 53 the hub of which is rotatably mounted on the shaft 35, the two sprockets being interconnected by a transmission chain 54. By this arrangement, both the tilting movement of the assembly 3| on the trunnions 38 and its bodily pivoting movement about the shaft 35 may be effected by concentrically arranged controls, since both the shaft 35 and the pinion 53 may rotate independently on the same axis.

Selective operation of the concentric controls is effected by a single hand wheel 56 that is rotatablymounted at the left side of the machine in a readily accessible position on a gear box 51 that is secured to the lower left upright of the frame member 2| below the discharge end of the drum 6. For effecting the bodily pivoting movement of the assembly 3| toward or from the drum opening Hi, there is provided a control rod 58 which extends from the gear box 5'! upwardly and is pivotally attached at its upper end to the outer end of an arm 59 fixed to and extending radially rearwardly from the end of the shaft 35 as shown in Figs. 1 and 2. Tilting movement of the assembly 3| about its trunnion axis is effected by a simi-- lar but offset control rod 6| that extends upwardly from the gear box 51 and is pivotally connected at its upper end to the outer end of an arm 62 secured to and extending radially forwardly from the hub of the sprocket 53 that is rotatably mounted on the shaft 35.

In effecting an interchange of the positions of the door element and the hopper element, the first operation is to move the control rod 58 upwardly by rotation of the hand wheel 56, thereby acting upon the radial arm 56 in a manner to turn the shaft 35 counterclockwise, thus pivoting the arms 31 and lifting the assembly 3| bodily outward and upward from the opening |6 in the drum HI. After the assembly 3| has been retracted in this manner to its elevated position, I

the control rod 6| is moved downwardly thereby turning the arm 62 and the sprocket 53 counter-- clockwise and through action of the chain 54 and the sprocket 52, causing the assembly 3| to be tilted upon its trunnions to the position shown in broken lines in Fig. 2. The control rod 58 may then be moved downwardly by operation of the hand wheel 56 to pivot the shaft 35 and lower the hopper element 33 into engagement with the charging opening I6, as shown in solid lines in Fig. 2.

Coordinated movements of the control rods 58 and 6| are effected by interlocked actuating mechanism Within the gear box or case 5'! and shown in detail in Figs. 6 and '7. As shown in Fig. 7, the actuating hand wheel 56 is rotatably mounted in a suitable 'bearing 64 secured to the outer face of the gear box or case 51. The hub of the hand wheel 56 is hollow and is internally splined to receive a shaft 65 which is axially slideable therein and extends through the bearing 64 into the gear case 51. As shown in Fig. '7 the shaft 65 is provided on its inner end with a pinion 66 and on its outer end with an actuating knob 61 secured thereto by a pin 68. By manipulating 6 the knob 61, the shaft may be moved endwise to shift the pinion 66.

With the shaft 65 in the inner position as shown in Fig, 7, the 'pinion 66 meshes with an inner gear wheel 69 that is fixed on a. shaft in rotatably mounted in the gear case 51 and extending therefrom at the rear side thereof. The extending end of the shaft 16 is provided with a crank arm H the outer end of which is pivotally connected to the lower end of the control rod 58, the arrangement being such that when the hand wheel 56 is turned, the pinion 66 turns the gear 69 and the crank 1| moves the control rod 58 up or down to effect bodily pivoting movement of the assembly 3| toward or from the charging opening l6 of the drum l6. Starting from the position of the mechanism shown in Figs. 2 to 7, in Which the hopper is shown applied to the drum opening I 6, rotation of the hand wheel 56 in the clockwise direction causes the gear 69 and crank 1| to turn counterclockwise thereby moving the rod 58 and the assembly 3| upward from the full line position to the broken line position shown in Fig. 2. In moving the assembly 3| into the retracted broken line position, the crank ll passes through its top dead center position and comes to rest against a stop 12 (Fig. 6), in an over-center position thereby retaining the assembly 3| in its elevated position.

By pulling outward on the control knob 61, the pinion 66 may be withdrawn from meshing engagement with the inner gear wheel 69 and shifted into meshing engagement with an outer gear wheel 14 fixed on a shaft 15 likewise rotatably mounted in the gear box 51 with one end projecting at the rear side thereof. The projecting end of the shaft 15 is similarly provided with a crank arm 76 that is pivotally connected at its outer end to the lower end of the control rod 6|. Upon turning the hand wheel 56 counterclockwise, the pinion 66 is now caused to rotate the gear 14 and the crank arm 16 clockwise thereby moving the control rod 6| upwardly from the position shown in Fig. 2 to the position shown in Fig. '1 which results in turning the arm 62 and the sprocket 53 clockwise to effect clockwise tilting of the assembly 3| about its trunnion axis, thereby pre senting the door element 32 toward the drum opening l6. In moving into the upper position, the crank 16 passes through its upper dead center position and into over-center engagement with the other side of the stop 12, thereby retaining the assembly in the selected position. The pinion 66 may then be moved back into meshing engagement with the inner gear wheel 69 by pushing inward on the actuating knob 61. Instead of employing the knob 61 for shifting the pinion 66, the hand wheel 56 may be secured directly to the shaft 65 in place of the knob, the shaft then being rotatably and slideably mounted in the bearing 64. Under these circmnstances, the hand wheel itself is moved axially to cheat end-wise shifting of the shaft 65 and the pinion 66.

When the pinion 66 is shifted out of engagement with the gear 14 by inward movement of the shaft 65, a locking latch or plunger 18 carried on the outer end of a pivotally mounted spring urged arm 19 is released for movement upward into locking engagement with the teeth of the gear wheel 74 to prevent accidental displacement of the assembly from its tilted position through operation of external forces. With the pinion 66 again engaged with the inner gear 69, the hand wheel 56 may then be turned counterclockwise to cause the crank 1| to turn out of its over-center position and move the control rod 58 downward thereby advancing the assembly 3 l downward toward the drum In.

As soon as the inner gear 89' is turned from the elevated or fully retracted position, one end of an arcuatev shroud plate or segment Bl secured to the face of the gear 69 moves in front of the face of the meshing. pinion 66 thereby constituting an interlocking or interference member which prevents the pinion from being shifted out of engagement with the gear 69. As turning of the hand wheel is continued, the cover element 32 is brought down into cooperating engagement with the end of the drum for closing the discharge opening fli, as shown in Fig. l, to adapt the mixer for the mixing and transporting operations. The cover is retained in the closed position by the force. of gravity and it may be locked in this or in other desired partially open positions, by means of a spring pressed locking plunger 83' that engages between the teeth of the gear E9, as shown in Fig. 6.

When it is desired to open the door 32 after the mixing operation for discharging concrete, the gear 69 is released by withdrawing the plunger 83 through operation of a hand lever 84 that is pivotally mounted on the outer end of the plunger and is provided with a cam surface 85 that cooperates with the outer end of a tubular housing 85 extending from the right side of the gear box 51 in a manner to withdraw the pliuiger by compressing a spring 8"! within the housing 85. As shown, the spring 8'! encircles the plunger 83 and is arranged to urge it into 1 engagement with the gear teeth. With the plunger 83 withdrawn, the gear 69 may be turned to elevate the hopper and door assembly 3i, whereupon the load of concrete may be discharged from the drum I!) through the discharging opening It by rotating the drum in the appropriate direction.

Since the shroud plate 8| prevents shifting of the pinion 66 out of engagement with the gear 59, the pinion 66 cannot be engaged with the gear 14 while the assembly is in lowered position and consequently the door and hopper cannot be tilted upon the trunnion axis until after the assembly is elevated out of interfering relationship with the end of the drum 10. As the assembly 3i arrives at its elevated position, the

end of the shroud plate 8| moves past the outer face of the pinion 66 thereby freeing it for subsequent shifting movement. With the assembly elevated, the locking plunger 83 may be moved inward to lock the gear 69 by action of the spring 81 upon moving the cam lever 84 to the position shown in Fig. 6, thereby retaining the assembly in elevated position.

The load of concrete having been discharged through the opening 16, and the pinion 66 now being free from interference with the shroud 8|, the pinion may be moved outwardly by pulling out on the actuating knob 61. As the pinion B approaches meshing engagement with the outer gear wheel 14, it engages a sloping or cam surface 89 on the spring urged arm 19 supporting the locking plunger 18, and forces it downward to move the plunger out of locking engagement with the teeth of the gear 74. This frees the gear 14 for rotation by the pinion 66 to tilt the assembly to the position shown in broken lines in Fig. 2 for substituting the hopper element 33 for the door element 32 as the active member of the combination. After the assembly 3| has been tilted, the pinion 66 may then be shifted inwardly by the knob 61 thereby releasing the spring pressed arm 19 for moving the plunger 18 again into locking engagement with the gear wheel M, the pinion 56 meanwhile moving past the end of the shroud ring 8| into meshing engagement with the inner gear 69. After the locking plunger 83 is again withdrawn, further movement of the hand wheel 56 then results in lowering the hopper into engagement with the charging opening as shown in Figs. 2 and 5, the interlocking shroud plate 81 meanwhile obviating the possibility of further tilting movement of the assembly 3|.

By substituting suitable cam mechanism or automatic shifting mechanism for the gearing shown in Figs. 6 and '7, the operation of elevating and tilting the assembly 3| for interchanging the hopper and door elements may be accomplished by continuous rotation of the hand wheel 56 without manual shifting of gearing. However, this would result in sacrificing a desirable degree of flexibility in operation which accrues from providing for manual shifting of the selective pinion 66. Furthermore, operation of the mechanism by power may be effected by providing a power drive to the pinion shaft 65 or by substituting hydraulic or air actuating mechanism with suitable interlocking controls for the mechanically interlocked mechanism in the gear case 51.

From the foregoing description and explanation of the operation of the improved concrete mixer charging apparatus set forth herein, it is apparent that there has been provided by the present invention a new and more convenient arrangement for cooperating with the charging opening of a truck-mounted concrete mixer whereby either a charging hopper element or a closure element may be applied to the opening through interchanging the two elements of a combined hopper and door assembly by the coordinated operation of interlocked actuating mechanism.

Although a specific embodiment of the invention has been described in detail by way of a full disclosure of preferred apparatus for practicing the invention, it is to be understood that the particular mechanism herein set forth constitutes merely one exemplification of the invention and that the structure shown may be modified to adapt it to various mixers and to their conditions of operation without departing from the spirit and scope of the invention as defined by the subjoined claims.

An exemplary embodiment of the invention having now been fully described, we claim as our invention:

1. In a concrete mixer of the elevated discharge type having a drum mounted for rotation upon an inclined axis and presenting a single charging and discharging opening concentric with its axis and at its elevated end, a frame arranged to support said rotatably mounted drum, a shaft rotatably mounted in said frame transversely thereof adjacent to and above said drum opening, a pair of arms fixed to and extending rearwardly and downwardly from said shaft in parallel relationship at opposite sides of said drum opening respectively, a combined hopper and door structure disposed between and rotatably mounted on the outer ends of said parallel arms and comprising a hopper element and a door element presentable alternatively toward said drum opening through tilting movement thereof relative to said drums,

a sprocket mounted on said hopper and door structure concentric with its axis of rotation, a complementary sprocket rotatably mounted on said shaft, a transmission chain operatively interconnecting said sprockets in such a manner that rotation of said sprocket on said shaft effects tilt ing movement of said hopper and door structure, and control mechanism operatively connected to rotate said sprocket or said shaft selectively, whereby said hopper and door structure may be tilted to present said hopper element or said door element toward said drum opening and said arms may be pivoted to move said structure bodily to engage said hopper element or said door element with said drum opening.

2. In a concrete mixer, a rotatably mounted mixing drum presenting a charging anddischarg ing opening, a combined hopper and door structure disposed to cooperate with'said drum opening to facilitate charging said drum or alternatively to close said opening during mixing, trunnions arranged to carry said combined hopper and door structure in a manner to provide for tilting said structure to present either the hopper element or the door element to said drum openingselectively, and pivotally mounted arms arranged to support said trunnions for rotary movement thereon, said arms being pivotally supported above said drum opening and operative when pivoted to move said hopper and door structure bodily toward or from said drum opening selectively.

3. In a concrete mixer, a mixing drum presenting in one end a-charging and discharging opening, a frame arranged to support said drum for rotation about an axis concentric with'said opening, a yoke pivotally mounted on said frame above said drum for swinging movement toward or from said drum opening, and a combined hopper anddoor rotatably mounted in said yoke and comprising a hopper element and a door element arranged to be presented alternatively toward said drum opening by appropriate tilting movement thereof in said yoke, the arrangement being such that whichever of said elements is presented toward said drum opening may be moved into cooperative relationship therewith by appropriate pivotal movement of said yoke relative to said frame.

4. In a concrete mixer having a mixing drum disposed with one end elevated and presenting a charging opening, a combined hopper and door structure disposed to cooperate with said charging opening, apparatus for effecting lowering or elevating movement of said combined structure toward or from said charging opening, apparatus for effecting tilting movement of said structure to present the hopper or the door toward said charging opening alternatively, and interlocking control mechanism interconnecting said actuating apparatus and including an interference member arranged to provide for operation thereof in such a manner asto effect tilting movement of said combined hopperand door structure only when said structure is elevated away from said charging opening, whereby interference between said drum and said structure during tilting thereof is obviated.

5. In a concrete mixer or the like, .a .frame adapted for mounting ona truck, amixingdrum rotatably mounted in said frame .with its axis inclined upwardly and rearwardly to: present an elevated discharge opening at the rear of the truck, a supporting shaft journalled transversely of said frame above said elevated opening, supporting arms attached to and extendingradially from said shaft, a combined hopper and door rotatably mounted on said arms for tilting movement to present either a hopper element or a door element toward said drum opening, a unitary control mechanism mounted on said frame below said drum in a readily accessible position and including pivoting mechanism and tilting mechanism, linkage operatively interconnecting said control mechanism with said shaft and with said combined hopper and door in such a manner that said shaft may be pivoted to raise or lower said hopper and door relative to said drum opening or said combined hopper and door may be tilted to present the one or the other to said drum opening, and interlocking apparatus operatively associated with said pivoting and tilting control mechanism and including an interference member movable with said pivoting mechanism and operative to prevent tilting movement of said combined hopper and door by said tilting mechanism except when said combined hopper and door is pivoted to raised position away from said drum opening.

6. In a concrete mixer of the inclined axis type presenting an elevated coaxial charging and discharging opening, a combined hopper and door structure presenting a hopper element and a door element adapted for alternative application to said opening, and interlocked control mechanism operative to move said hopper and door structure bodily toward or retract it from said mixer opening and including actuating elements operative only when said structure is retracted from said opening to position said structure for presenting either said hopper element or said door element selectively for movement into cooperating relationship with-said opening.

7. A concrete mixer comprising a frame, a mixing drum rotatably mounted in said frame and presenting a charging and discharging opening concentric with its axis of rotation, a shaft rotatably mounted in said frame transversely thereof adjacent to and above said drum opening, a pair of supporting arms attached to and extending rearwardly and downwardly from said shaft in spaced relationship, and a combined hopper and door disposedbetween and rotatably mounted on said arms and constituted by a hopper element and a door element arranged to be presented toward said drum opening alternatively by appropriate tilting movement thereof relative to said arms and to be-movedbodily-towardor from said drum opening byappropriate pivotal movement of said arm carrying shaft, the arrangement being such that either said hopper or said door may be appliedto said drum opening selectively.

8. Ina concrete mixer having a frame and a mixing drum rotatably mounted in said frame and presenting a chargingand discharging opening, a charging hopper disposed to cooperate with said drum opening infacilitating charging. of said drum, a door likewise disposedto cooperate with said drum opening to close it during a mixing operation, -means movably supporting said hopper-and said dooron said frame, and control linkage operatively arranged to move the one or the other of saidhopper and said door into register with said drum opening selectively, said control linkage including an interference member arranged to interlock .saidcontrol linkage in such a manner that interference between said hopper, said door. and said drum is obviated.

-9. In aconcretemixer havinganinclined mixing drum presenting a'charging opening in its elevated end and a cooperatingcombined hopper and door tiltable to present a charging hopper or a closure door to said drum opening alternatively, a control mechanism for operating said combined hopper and door comprising a gear box including a gear for effecting tilting movement of said combined hopper and door relative to said mixing drum opening and another gear for effecting lowering or elevating movement of said combined hopper and door bodily towards or from said mixing drum opening, linkage operatively interconnecting said gears with said combined hopper and door structure in a manner to efiect said movements respectively upon turning movement of the appropriate one of said gears, a shiftable pinion disposed to be shifted into engagement with the one or the other of said gears alternatively to effect the corresponding movement of said combined hopper and door, a hand wheel operatively connected to effect turning movement of said pinion, and an interlocking interference plate associated with said hopper and door elevating gear and operative to prevent disengaging movement of said pinion from said gear except when said gear is in the position corresponding to the fully elevated position of said combined hopper and door, whereby said pinion cannot be shifted into engagement with said hopper and door tilting gear except when said hopper and door is in elevated position thereby preventing tilting movement thereof in any position in which interference with said mixing drum would otherwise occur.

10. In a concrete mixer of the inclined axis rotary drum type presenting a charging and discharging opening at its elevated end, a combined hopper and door structure for cooperating with said opening, said combined structure comprising a hopper element for facilitating charging the drum through said opening and a door element to close said opening during mixing, said elements being arranged to engage said opening alternatively, a yoke movably supporting said combined hopper and door structure for movement to present said hopper element or said door element to said opening selectively, a frame movably supporting said yoke for bodily movement of said combined hopper and door toward or from said drum opening to engage said hopper or said door with said drum opening, control apparatus operatively arranged to efiect movement of said combined hopper and door relative to said yoke and bodily movement thereof relative to said drum opening, and interlocking mechanism operatively associated with said control apparatus and including an interference member operative to prevent movement of said combined hopper and door relative to said yoke except after operation of said control apparatus to displace said combined hopper and door bodily from said drum.

11. Concrete mixing apparatus or the like including a drum presenting a charging opening, a combined hopper and door structure for cooperating therewith comprising a hopper element and a door element adapted to be engaged with said charging opening alternatively and joined to constitute a unitary structure, a yoke arranged to support said combined structure for tilting movement in a manner to present said hopper element or said door element toward said charging opening selectively, and a supporting frame pivotally supporting said yoke above said drum charging opening in a manner to provide for bodily pivotal movement of said combined structure toward or from said charging opening, the

.12 arrangement being such that either said hopper element or said door element may be engaged with said charging opening by appropriate tilting movement of said combined structure in said yoke and pivotal movement of said yoke relative to said supporting frame.

12. In a concrete mixer of the rotary drum type with the drum presenting a charging and discharging opening, a combined hopper and door structure for cooperating with said opening, said combined structure comprising a hopper element for facilitating charging the drum through said opening and a door element to close said opening during mixing, said elements being arranged to engage said opening alternatively, a yoke movably supporting said combined hopper and door structure for tilting movement to present said hopper element or said door element to said opening selectively, and a shaft disposed above and transversely of the drum and pivotally supporting said yoke for bodily movement of said combined hopper and door toward or from said drum opening, whereby either said hopper or said door may be engaged with said drum opening selectively.

13. In a concrete mixer of the type having a rotary mixing drum presenting a coaxial charging and discharging opening, a combined hopper and door structure disposed to cooperate with said drum opening, said structure comprising a hopper element, a trunnion element adjustably mounted on the back of said hopper element'and a circular door rotatably mounted on said trunnion element in back-to-back relationship with said hopper element; a yoke arranged to engage said trunnion element in a manner to support said combined structure for tilting movement about the axis of said trunnion element to present the one or the other of said hopper element and door element toward said drum opening, and a transverse shaft arranged above said drum opening and movably supporting said yoke in a manner to effect bodily movement of said combined structure toward or away from said drum opening, whereby either said hopper element may be disposed in adjusted cooperating relationship with said drum opening during charging of said drum or said door element may be engaged with said drum opening to rotate with said drum while maintaining said opening closed during mixing of the charge.

14. In a transit concrete mixer of the truckmounted type, a mixing drum presenting a charging and discharging opening, a combined hopper and door structure arranged to cooperate with said drum opening to facilitate charging or alternatively to close said opening during mixing, controlling and actuating apparatus for positioning said combined structure relative to said opening, said apparatus comprising a gear wheel operatively connected to effect tilting movement of said combined structure for presenting the hopper or the door element thereof toward said opening and another gear wheel operatively connected to effect bodily movement of said combined structure toward or from said opening, a pinion slidably mounted for shifting into meshing engagement with the one or the other of said gear wheels selectively, actuating means connected to effect rotation of said pinion to operate the gear wheel with which it is meshed, an interference interlock associated with said bodily movement gear wheel and operative to prevent meshing of said pinion with said tilting gear wheel except when said combined struc- 13 ture is retracted from said opening, a manually actuated latch associated with said bodily movement gear wheel and selectively operable to lock said gear wheel for retaining said structure in selected position relative to said drum opening,

and a resiliently urged latch associated with said tilting movement gear wheel and operative to engage and lock said gear wheel when said pinion is disengaged therefrom, said latch being positioned for retraction by said pinion in moving into engagement with said gear wheel thereby freeing said gear wheel for rotation by said pinion.

15. In a concrete mixer or the like, a frame adapted for mounting on a truck, a mixing drum rotatably mounted in said frame with its axis inclined upwardly and rearwardly to present an elevated discharge opening at the rear of the truck, a supporting shaft journalled transversely of said frame above said elevated opening, supporting arms attached to and extending radially from said shaft, a combined hopper and door structure rotatably mounted on said arms for tilting movement to present either a hopper element or a door element thereof toward said drum opening, a unitary control mechanism mounted on said frame beneath said drum in a readily accessible position, linkage operatively interconnecting said unitary control mechanism with said shaft and with said combined hopper and door structure in such a manner that said shaft may be pivoted to raise or lower said combined structure relative to said drum opening or said combined structure may be tilted to present the one or the other of said hopper and door elements to said drum opening, and a single actuating member operatively associated with said control mechanism and operative thereon to effect pivoting of said shaft to raise said arms and then tilting movement of said hopper and door structure when said structure is in raised position away from said drum opening.

16. In a concrete mixer having an inclined mixing drum presenting a charging opening in its elevated end and a cooperating combined hopper and door tiltable to present a charging hopper or a closure door to said drum opening alternatively, a control mechanism for operating said combined hopper and door comprising, a gear box including a gear for effecting tilting movement of said combined hopper and door relative to said mixing drum opening and another gear for effecting lowering or elevating movement of said combined hopper and door bodily towards or from said mixing drum opening, linkage operatively inter-connecting said gears with said combined hopper and door structure in a manner to effect said movements respectively upon turning movement of the appropriate one of said gears, a shiftable pinion disposed to be shifted into engagement with the one or the other of said gears alternatively to effect the corresponding movement of said combined hopper and door, and a single hand wheel operatively connected to effect turning movement of said pinion, whereby said pinion may be shifted into engagement with said hopper and door tilting gear or with said hopper and door elevating gear to provide either of said movements by operation of said single hand wheel.

17. In a transit concrete mixer of the truckmounted type, a mixing drum presenting a charging or discharging opening, a combined hopper and door structure arranged to cooperate with said drum opening to facilitate charging or to close said opening during mixing, controlling and actuating apparatus for positioning said combined structure relative to said opening, said apparatus comprising a gear wheel operatively connected to effect tilting movement of said combined structure for presenting the hopper or the door element thereof toward said opening and another gear wheel operatively connected to effect bodily movement of said combined structure toward or from said opening, a pinion slideably mounted for shifting into meshing engagement with the one or the other of said gear wheels selectively, and actuating means connected to effect rotation of said pinion to operate the gear wheel with which it is meshed.

18. In a transit concrete mixer of the truckmounted type, a mixing drum presenting a charging or discharging opening, a combined hopper and door structure arranged to cooperate with said drum opening to facilitate charging or to close said opening during mixing, controlling and actuating apparatus for positioning said combined structure relative to said opening, said apparatus comprising a gear wheel operatively connected to effect tilting movement of said combined structure for presenting the hopper or the door element thereof toward said opening and another gear wheel operatively connected to effect bodily movement of said combined structure toward or from said opening, a pinion slideably mounted for shifting into meshing engagement with the one or the other of said gear wheels selectively, actuating means connected to effect rotation of said pinion to operate the gear wheel with which it is meshed, and a manually actuated latch associated with said bodily movement gear wheel and selectively operable to lock said gear wheel for retaining said structure in selected position relative to said drum opening.

19. In a transit concrete mixer of the truckmounted type, a mixing drum presenting a charging or discharging opening, a combined hopper and door structure arranged to cooperate with said drum opening to facilitate charging or to close said opening during mixing, controlling and actuating apparatus for positioning said combined structure relative to said opening, said apparatus comprising a gear wheel operatively connected to effect tilting movement of said combined structure for presenting the hopper or the door element thereof toward said opening and another gear wheel operatively connected to effect bodily movement of said combined structure toward or from said opening, a pinion slideably mounted for shifting into meshing engagement with the one or the other of said gear wheels selectively, actuating means connected to eifect rotation of said pinion to operate the gear wheel with which it is meshed, a resiliently urged latch associated with said tilting movement gear wheel and operative to engage and lock said gear wheel when said pinion is disengaged therefrom, and means operated by said pinion in moving into engagement with said gear wheel to retract said latch thereby freeing said gear wheel for rotation by said pinion.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,058,803 Smith Apr. 15, 1913 2,338,820 Peters Jan. 11, 1944 2,447,413 Joseph Aug. 17, 1948 2,578,170 Bohmer Dec. 11, 1951 

